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Commit c715089f authored by Chris Wilson's avatar Chris Wilson Committed by Eric Anholt
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drm/i915: Handle ERESTARTSYS during page fault 



During a page fault and rebinding the buffer there exists a window for a
signal to arrive during the i915_wait_request() and trigger a
ERESTARTSYS. This used to be handled by returning SIGBUS and thereby
killing the application. Try 'cairo-perf-trace & cairo-test-suite' and
watch X go boom!

The solution as suggested by H. Peter Anvin is to simply return NOPAGE and
leave the higher layers to spot we did not fill the page and resubmit
the page fault.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
[anholt: Mostly squash it with another commit]
parent ab18282d

drivers/gpu/drm/i915/i915_gem.c

+12 −17
Original line number Diff line number Diff line
@@ -1200,26 +1200,21 @@ int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 
	mutex_lock(&dev->struct_mutex);

	if (!obj_priv->gtt_space) {

		ret = i915_gem_object_bind_to_gtt(obj, 0);

		if (ret) {

			mutex_unlock(&dev->struct_mutex);

			return VM_FAULT_SIGBUS;

		}

		if (ret)

			goto unlock;



		list_add_tail(&obj_priv->list, &dev_priv->mm.inactive_list);



		ret = i915_gem_object_set_to_gtt_domain(obj, write);

		if (ret) {

			mutex_unlock(&dev->struct_mutex);

			return VM_FAULT_SIGBUS;

		}

		if (ret)

			goto unlock;

	}



	/* Need a new fence register? */

	if (obj_priv->tiling_mode != I915_TILING_NONE) {

		ret = i915_gem_object_get_fence_reg(obj);

		if (ret) {

			mutex_unlock(&dev->struct_mutex);

			return VM_FAULT_SIGBUS;

		}

		if (ret)

			goto unlock;

	}



	pfn = ((dev->agp->base + obj_priv->gtt_offset) >> PAGE_SHIFT) +
@@ -1227,18 +1222,18 @@ int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 


	/* Finally, remap it using the new GTT offset */

	ret = vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);



unlock:

	mutex_unlock(&dev->struct_mutex);



	switch (ret) {

	case 0:

	case -ERESTARTSYS:

		return VM_FAULT_NOPAGE;

	case -ENOMEM:

	case -EAGAIN:

		return VM_FAULT_OOM;

	case -EFAULT:

	case -EINVAL:

		return VM_FAULT_SIGBUS;

	default:

		return VM_FAULT_NOPAGE;

		return VM_FAULT_SIGBUS;

	}

}